1. Field of the Invention
This patent relates to a means for protecting from fire industrial size liquid holding containers. More particularly, this patent relates to a means for protecting from warehouse fires intermediate bulk containers having a non-metallic inner container supported by a steel cage and resting on a pallet.
2. Description of the Related Art
Industrial size containers for holding liquids (eg., drums, bulk totes and intermediate bulk containers) made from non-metallic materials of construction may be used for transporting flammable and combustible liquids, but they have not yet been approved by appropriate fire protection agencies and insurance underwriters for use in storing such materials in "protected" warehouses. Experience has shown that when intermediate bulk containers, or IBCs, having a steel support cage are exposed to fire, the steel cage heats up, causing a transfer of heat from the steel cage to the plastic inner container exceeding the transfer of heat from the plastic inner container to the liquid contents (acting as a heat sink), resulting in an increase in the temperature of the plastic inner container. If the heat exposure from a fire is great enough, the plastic inner container will melt along those areas where the steel cage contacts the inner container. If failure of the inner container occurs, the flammable contents may spill out and be exposed to the fire, making it extremely difficult to extinguish the blaze. As a result, a significant market for IBCs having inner containers made from non-metallic materials of construction has heretofore been foreclosed, or at least made difficult to serve.
The present invention solves this problem by incorporating a fire protective cover into the IBC design. By maintaining the temperature of the inner container where it contacts the metal support structure at less than melting temperature even in the presence of an intense warehouse fire, the invention allows the survival of the non-metallic IBC inner container for a time sufficient for alternative fire protection means (e.g., sprinklers, fire service personnel with water or foam spray fire suppression equipment) to be deployed.
Fire protective devices are well known in the art. None, however, solves the problem of protecting non-metallic flammable liquid holding containers from warehouse fires. For example, Szego U.S. Pat. No. 4,249,669 discloses a blanket of porous, heat resistant material that floats on the surface of a flammable liquid held within a tank. On ignition of the vapor/air mixture above the liquid the flames recede downwardly until they are extinguished when they reach the blanket. The Szego blanket is not suitable for covering the outside of a steel-cage supported liquid bulk container because, among other reasons, the blanket is porous and allows air to pass through it. By contrast, the present invention requires a nonporous cover which, when exposed to warehouse pool fires, creates an oxygen depleted space between the cover and the liquid holding container.
Peterson U.S. Pat. No. 5,104,700 teaches a fire protective blanket for fireproofing articles such as electrical conductors, cables, pipes, and electric motors. The blanket comprises a plurality of layers of thick but compressible insulative material held together by fasteners that are less resistant to heat than the insulative layers. When the blanket is exposed to heat, the fasteners fail, allowing the blanket to decompress or expand in thickness. This device is not intended for use with flammable liquid holding containers, nor is it suitable as such. Among other things, the Peterson blanket requires a certain minimum thickness in order to achieve its fire protection function, making it unwieldy for use with industrial sized liquid holding containers. By contrast, as will be shown, the present invention requires very little thickness to protect the liquid holding container from heat. Instead, the cover acts in tandem with the liquid contents of the container which operates as a heat sink to keep the container below the temperature at which it will melt or fail.
In brief summary, the fire resistant blankets disclosed in the prior art generally are directed toward keeping flames away from pipes, valves, motors, and other electrical equipment, whereas the present invention is directed toward protecting from fire non-metallic flammable liquid holding containers, particularly those having a metal support cage and resting on a pallet.
Thus it is an object of the present invention to provide a means for protecting non-metallic flammable liquid holding containers from fire which possesses all of the aforenoted advantages.
A further object of the present invention is to provide a fire protective cover that acts in tandem with the contained liquid product/heat sink to keep a non-metallic inner container below the temperature at which the inner container will melt.
A still further object of the present invention is to provide a fire protective cover that, when exposed to typical warehouse fire conditions, creates an oxygen depleted space between the cover and the inner container.
Another object of the present invention is to provide a fire protective cover that requires less insulating capacity and is thinner than conventional fire protective covers, thus allowing ease of installation and removal and ease of storage when the covers are not in use.
Another object of the present invention is to provide a fire protective cover for non-metallic liquid holding containers that is easy to manufacture and economical to use.
Yet another object is to provide a fire protective cover that is suitably thin so that the containers being protected may be stacked one on top of another under standard warehouse storage conditions.
Further and additional objects will appear from the description, accompanying drawings, and appended claims.